Method of cracking hydrocarbon oils



HAZJMS v F. MANLEY METHOD OF CRACKING HYDROCARBON OILS Filed 001'.. 10

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@Hoz ne 15 Patented Jury 17, 1923.

UNITED STATES PATENT oFFlcE.

FREDERICK T. MANLEY, OF HOUSTON, TEXAS, ASSIGNOR T0 THE TEXAS COMPANY, OF NEW YORK, N. Y.,\A CORPORATION OF TEXAS.

METHOD 0F ORACKING EYDROCARBON OILS.

Application led October 10, 1917. Serial No. 195,775.

To all whom 'it may concern:

Be it known that I, FREDERICK T. MANLEY, a citizen of the United States, residing in Houston, Harris County, and State of Texas, have invented certain new and useful Improvements in Methods of Cracking Hydrocarbon Oils, of which the following is a specification.

This invention relates to novel processes by which higher-boiling hydrocarbons are decomposed or broken up into lower-boiling hydrocarbons. It relates particularly to the cracking of such oils as kerosene, gas oil, lubricating oil, and the like, for the production of more volatile produc-ts, such as are usually designated by such terms as gasoline and naphtha. More especially it relates to novel and improved processes by which is effected the decomposition of certain of the more readily volatilized constituents which areformed in cracking the higher-'boiling hydrocarbons, and which, although not suiiiciently volatile for gasoline` or naphtha are yet so readily volatilized that it is diiiicult under existing practices to hold them within a Zone of sufficient heat to decompose them.

In the practice of cracking hydrocarbons for the production of the more volatile products, as gasoline, considerable diiiiculty has hitherto been experience-d in'the proper disposal of the large proportion of constituents of the kerosene type usually formed when using the requisite pressures and temperatures needed for cracking the hydrocarbons which it is commonly sought to decompose into gasoline. Attempts have been made to effect a cracking ofthese constituents by returning them to the still by such methods as the use of inclined vapor lines and traps of various kinds, but the volatility of said constituents is such that upon coming in contact with the vapor portion of the still they are vaporized by the heat without, however, being heated sufliciently for decomposition. The result is that these constituents of the kerosene type tend to collect i n great quantitics in the upper portions of the still and in the vapor lines leading therefrom. They are too heavy to be used for the gasoline fractions, yet ae so easily volatilized that they do not drop back into a Zone of sufficient heat to decompose theminto lighter products. As a result of the accumulation of these kerosene constituents the operator is forced to increase the pressures used, thus augmenting the danger, as well as the expense of carrying on the operation. It is an object of this invention to collect these constituents of the kerosene type, return them directly to the bottom of the still into which they are positively forced and retain them there for a suflicient time to decompose them into more volatile products.

Certain novel apparatus for carrying out the herein disclosed process is illustrated in the accompany drawing, but is not claimed herein as it is made the subjectof my copending application Serial No. 195,774, filed October 10, 1917.

In the drawings,

Figure 1 shows partly in vertical section an apparatus adapted tocarry out my invention; and

Figure 2 isan enlarged section of a portion of the cracking tube showing scraping means therein. f

Referring to the drauf'ing,-a cracking still 4, with suitable supports 9 heated intermediate its ends. is placed in a furnace l, having baffle Walls 3, burner 2 and stack 13. A vapor line 5 extends from the upper portion of the cracking still above the heating-zone to an air condenser 6. A return conduit 7 reaches from the air condenser directly to the lower portion of the cracking still 4 below the heating zone in order to return condensed material. 8 is a valved draw-off pipe at the bottom of the cracking still 4.

The still is preferably equipped with a supply pipe 10 entering the horizontal section of the conduit 7 whereby the introduction of the oil charge is caused to produce an injector effect by which the material in the pipe 7 may be forced into the still.

A vapor line 15 extends from the air co-ndenser 6 to suitable water condensers 28. The outlet from the condenser 28 has a valve 29. 16 denotes a pressure gauge on the air condenser to indicate the vapor pressure therein. 17 and 18 designate recording thermometers on the air condenser and cracking still, respectively, and 19 and 30 furnace pyrometers. A gauge 14 for indicating the lliquid level in the still 4 is situated at the up er part thereof. f

n .this form of apparatus the oil in the cracking still 4 forms an extended vertical Too y column and the charging oil and condensate 'forcibly supplied at the bottom, passes up through that column and is thus subjected to the crackin operation. In order to keep the inner surface of the cracking still clean and prevent the collection of material on v that surface, I preferably provide a scraping rods 27, around which are placed coiled s rin s 26 to ieldingly press the brushes argaint the inngr surface of the still 4. The shaft 24 may be driven through a worm gear 21 from thev shaft 22. In order to support the shaft at its upper end I preferably mount a pipe 20 in the upper end of the still 4 slightly larger in diameter than the 'shaft 24, and at the upper end of this pipe 20 'I place a stufling boX 23. The purpose of this pipe 20 is to place the stuffing box m a relatively cool position. The .brushes in the still 4 are placed only in the cracking zone which, as illustrated in Figure 1, is between the parts marked 4a and 4b.

The heating arrangements of the furnace are such that the hot combustion gases pass upward from the burner 2 between the furnace wall 1 and baffle 3 until they are de- Hected by the top wall of the furnace into the heating chamber which contains the cracking still andvis formed by the battle 3. The hot gases pass downwardly imparting heat to the cracking still and lind exit at 31 to and through the stack 13. The upper and lower ends of the cracking still preferabl extend beyond the heating. zone.

15x71 the operation of my process, I charge the still 4 with the hydrocarbon oil which it is desired to decompose into lighter products, such as gasoline. The liquid level throughout the operation is maintained at a point above the heating zone in the upper portion of the still. By regulating the supply of oil entering the still through the charging line 10, hydrocarbon in the cracking still is ordinarily heated to from 650 to 800 F., the exact temperature needed being dependent upon the character of the charge. I maintain and regulate pressure in the apparatus by means of the valve 29, in the condenser outlet. I use a pressure not ordinarily below 100 lbs. and may employ one as high as 300 lbs. The vapors generated pass out from the cracking still through the vapor line 5 to the air condenser. The constitutents of the desired volatility, that is, ordinarily those of the gasoline or naphtha type, are carried to the water condensers by the conduit 15.

The less volatile constituents, that is, ordinarily predominantly those of the kerosene type are liquefied in the air condenser and dropped down into the return conduit its boiling point is below the mean boiling point of the contents of the still it tends to vaporize comparatively rapidly thereby creating a current up through the liquid column. the light hydrocarbons being generated in the cracking operation and serves to remove them from the cracking zone as formed, thus preventing decomposition of the light liquefiablc hydrm'arbous into pciiiianent. gases.

By reason of the extent of the cracking zone the returned condensate is subjected to a cracking temperature for a sulicient time to cause the conversion of substantial portions thereof into the desired volatile products. The operation is cyclic, the heavier condensates collecting in the separator 6 continuously being returned to the cracking still 4 and passed upward through the heated liquid column` thus continuously decomposing these returning constituents into lighter and more volatile products. In this manner the constituents of thc kerosene type, which have hitherto been found so difficult to crack, may readily be decomposed into the desired products. By carrying on the cracking in the liquid phase the conversion is effected without heating the hydrocarbons unduly or unevenly thus avoiding undue carbonization and the formation of excessive quantities of gas or of unsaturated compounds.

By continuously returning to the cracking still 4 the condensate collected in the separator 6 the zone of reaction in the cracking still 4 is saturated with hydrocarbons of the kerosene type thus bringing about a chemical equilibrium tending to a reduction in the formation of this type of hyrocarbons and making possible an increased formation of the gasolene products desired.

The tube 7 is insulated so as to prevent undue loss in heat by the products passing through it. B v returning these constituents to the heating zone while still in a heated condition a considerableeconoiny is effected in the amount of fuel required to carry on the cracking operation. i

The volatile product desired leaves the separator 6 in the form of vapor and -is con- This current acts as a carrier of c ducted by the vapor line 15 to the condenser i 28 whereinithe product is condensed, the condensate being withdrawn through the -valved outlct 29. The residue collecting in rau will vary not only' with the character of the hydrocarbon oil introduced into the still,

`but with the temperature and pressures employed,'and with other variable factors, as the speed ot the operation. so that in the normal operation ot' the process certain constituents may be returned which may not come strictly within the meaning ot' the term kerosene asthat word is commonly employed in the Aart. But I prefer to use the word kerosene i herein, since in the normal operation of the process the returned constituents are predominantly those ot the kerosene type. It -is understood that by mea-ns of my process the products generated by the cracking operation. which are less volatile than desired, and which either through the readiness with which they are vaporizcd. or on account of mechanical action or other cause, pass out from the cracking zone, are continuously and directly returned to the cracking '/.one and -are forced through the heated liquid column' .so that these constitutents are all eventuallyv decomposed into products ot the gasoline or naphtha type.

That l claim and desire to secure by Letters Patent is:

l. The continuous method ot cracking hydrocarbon oils which comprises charging the oil into an elongated vertical still to maintain Vtherein an extended column ot liquid oil, maintaining said column of oil under temperature and pressure sutiicient tor cracking. collecting the generated vapors and separating therefrom the less volatile constituents thereof. continuously and directly returning said less volatile constituents and positively forcing them into the bottom of the still so that they are caused to pass through substantially the full length of the extended column ot oil therein. and condensing the constituents ot desired volatility.

Q. The continuous method of cracking hydrocarbon oils which comprises charging the oil into an elongated vertical still to maintain therein an extended column ot liquid oil. maintaining said column of oil at a temperature and pressure sutiicient tor cracking. removing residue and vapors from the stillto maintain a substantially constant liquid level therein. separating out the heavier constituents of said vapors and directly returning said constituents in cyclic passage through substantially the full length of the extended column of oil by positively forcing them into the bottom of the still.

3. The continuous method ot cracking hydrocarbon oils that comprises charging the oil into the bottom of an elongated vertical still to maintain an extended column of liquid oil therein. maintaining said column of oil under sutlicient heat and pressure for cracking, separating out the heavier constituents of the evolved vapors, and directly returning and injecting them with the charging oil into the bottom of the still so that they are caused to pass through substantially the full length of the extended column of oil therein.

sl. The continuous method ot cracking hydrocarbon oils that comprises charging the oil into a vertical still to maintain therein anv extended' column of liquid oil, heating said column of oil intermediate the ends of the still to maintain a cracking temperature therein. allowing the generated vapors to collect in the upper end ot the still above the portion thereof to which heat is applied, continuously removing the collected carbon formed and causing it to collect at the bottom of the still below the heating zone, con-* trolling 'the removal of the vapors from the still to maintain therein a superatmospheric pressure. separating out the heavier constituents of the vapors and directly returning saidv constituents in cyclic passage through substantially the full length of said column of oil by forcing them together with the charging oil into the bottom of the still.

5. The continuous method of cracking hydrocarbon oils which comprises charging the oil into an elongated vertical still to maintain therein an extended column of liquid oil. maintaining said column of oil under temperature and pressure sutiicient for cracking. collecting the generated vapors, cooling said vapors to condense the heavier constituents thereof. preventing further cooling ot the resulting condensate and directly returning same in a heated condition and positively forcing it together with the charging oil into the bottom of the still so that the condensate is caused to pass through substantially the full length of the extended column of oil therein.

6. The continuous method of cracking hydrocarbon oils which comprises charging a stream of oil into the bottom of a cracking still to maintain a body of oil therein, maintaining the oil therein under pressure and at a cracking temperature, removing the evolved vapors. separating out the heavier' constituents thereof. and returning them directly to the still for further treatment by positively forcing them in the stream of charging oil into the bottom of the still.

7. The continuous method of cracking hydrocarbonoils which comprises charging the oil into an elongated vertical still to maintain an extended column of liquid oil therein, maintaining said column of oil under temperature and pressure sufficient for cracking, collecting the generatedvapors, separating therefrom the less volatile constituents, and positively forcing them into the bottom of the still so that they are caused to pass through substantially the full length of the extended column of oil therein.

"8. The continuous method of cracking..

hydrocarbonoils which comprises charging the oil into a still to maintain a body of oil therein, subjecting the oil therein to crack- 5 ing temperature and pressure,'ren1oving the evolved vapors, separating out the heavier constituents thereof, and returning them in heated condition in cyclic passage to the still for further treatment by positively forcing them into the bottom of the still. no

In testimony whereof I do aix my signature.

FREDERICK fr. MANLEY. 

